#include <stdio.h>
#include "debug.h"
#include "object.h"

void disassembleChunk(Chunk *chunk, const char *name) {
    printf("==== %s ====\n", name);

    for(int offset = 0; offset < chunk->count;) {
        offset = disassembleInstruction(chunk, offset);
    }
}

static int simpleInstruction(const char *name, int offset) {
    printf("%s\n", name);
    return offset + 1;
}

static int constantInstruction(const char *name, OpCode code, Chunk *chunk, int offset) {
    uint32_t constant;
    int instructionOffset;
    if (code == OP_CONSTANT_LONG || 
        code == OP_DEFINE_GLOBAL_LONG ||
        code == OP_SET_GLOBAL_LONG ||
        code == OP_GET_GLOBAL_LONG
    )  {
        constant = 0;
        for(int i = 0; i <= 2; i++) {
            constant |= (chunk->code[offset + i + 1] << ((2 - i) * 8));
        }

        instructionOffset = 4;
    } else {
        constant = chunk->code[offset + 1];
        instructionOffset = 2;
    } 

    printf("%-16s %4d '", name, constant);
    printValue(chunk->constants.values[constant]);
    printf("'\n");
    return offset + instructionOffset;
}

static int byteInstruction(const char* name, Chunk* chunk, int offset) {
    uint8_t slot = chunk->code[offset + 1];
    printf("%-16s %4d\n", name, slot);

    return offset + 2;
}

static int jumpInstruction(const char* name, int sign, Chunk* chunk, int offset) {
    uint16_t jump = (uint16_t) (chunk->code[offset + 1] << 8);
    jump |= (uint16_t) (chunk->code[offset + 1] << 8);
    jump |= chunk->code[offset + 2];
    printf("%-16s %4d -> %d\n", name, offset, offset + 3 + sign * jump);
    return offset + 3;
}
 
static int invokeInstruction(const char* name, Chunk* chunk, int offset) {
    uint8_t constant = chunk->code[offset + 1];
    uint8_t argCount = chunk->code[offset + 2];
    printf("%-16s (%d args) %d '", name, argCount, constant);
    printValue(chunk->constants.values[constant]);
    printf("' \n");
    return offset + 3;
}

int disassembleInstruction(Chunk *chunk, int offset) {
    printf("%04d ", offset);
    if (offset > 0 && chunk->lines[offset] == chunk->lines[offset - 1]) {
        printf("   | ");
    } else {
        printf("%4d ", chunk->lines[offset]);
    }

    uint8_t instruction = chunk->code[offset];
    switch (instruction) {
        case OP_CONSTANT_LONG:
            return constantInstruction("OP_CONSTANT_LONG", OP_CONSTANT_LONG, chunk, offset);
        case OP_GET_GLOBAL_LONG:
            return constantInstruction("OP_GET_GLOBAL_LONG", OP_GET_GLOBAL_LONG, chunk, offset);
        case OP_GET_LOCAL:
            return byteInstruction("OP_GET_LOCAL", chunk, offset);
        case OP_GET_UPVALUE:
            return byteInstruction("OP_GET_UPVALUE", chunk, offset);
        case OP_GET_PROPERTY:
            return constantInstruction("OP_GET_PROPERTY", OP_GET_PROPERTY, chunk, offset);
        case OP_DEFINE_GLOBAL_LONG:
            return constantInstruction("OP_DEFINE_GLOBAL_LONG", OP_DEFINE_GLOBAL_LONG, chunk, offset);
        case OP_SET_GLOBAL_LONG:
            return constantInstruction("OP_SET_GLOBAL_LONG", OP_SET_GLOBAL_LONG, chunk, offset);
        case OP_SET_LOCAL:
            return byteInstruction("OP_SET_LOCAL", chunk, offset);
        case OP_SET_UPVALUE:
            return byteInstruction("OP_SET_UPVALUE", chunk, offset);
        case OP_SET_PROPERTY:
            return constantInstruction("OP_SET_PROPERTY", OP_SET_PROPERTY, chunk, offset);
        case OP_CONSTANT:
            return constantInstruction("OP_CONSTANT", OP_CONSTANT, chunk, offset);
        case OP_NIL:
            return simpleInstruction("OP_NIL", offset);
        case OP_FALSE:
            return simpleInstruction("OP_FALSE", offset);
        case OP_TRUE:
            return simpleInstruction("OP_TRUE", offset);
        case OP_POP:
            return simpleInstruction("OP_POP", offset);
        case OP_GET_GLOBAL:
            return constantInstruction("OP_GET_GLOBAL", OP_GET_GLOBAL, chunk, offset);
        case OP_DEFINE_GLOBAL:
            return constantInstruction("OP_DEFINE_GLOBAL", OP_DEFINE_GLOBAL, chunk, offset);        
        case OP_SET_GLOBAL:
            return constantInstruction("OP_SET_GLOBAL", OP_SET_GLOBAL, chunk, offset);
        case OP_EQUAL:
            return simpleInstruction("OP_EQUAL", offset);
        case OP_LESS:
            return simpleInstruction("OP_LESS", offset);
        case OP_GREATER:
            return simpleInstruction("OP_GREATER", offset);
        case OP_ADD:
            return simpleInstruction("OP_ADD", offset);
        case OP_SUBTRACT:
            return simpleInstruction("OP_SUBTRACT", offset);
        case OP_MULTIPLY:
            return simpleInstruction("OP_MULTIPLY", offset);
        case OP_DIVIDE:
            return simpleInstruction("OP_DIVIDE", offset);
        case OP_NOT:
            return simpleInstruction("OP_NOT", offset);
        case OP_NEGATE:
            return simpleInstruction("OP_NEGATE", offset);
        case OP_PRINT:
            return simpleInstruction("OP_PRINT", offset);
        case OP_JUMP_IF_FALSE:
            return jumpInstruction("OP_JUMP_IF_FALSE", 1, chunk, offset);
        case OP_JUMP:
            return jumpInstruction("OP_JUMP", 1, chunk, offset);
        case OP_LOOP:
            return jumpInstruction("OP_LOOP", -1, chunk, offset);
        case OP_CALL:
            return byteInstruction("OP_CALL", chunk, offset);
        case OP_INVOKE:
            return invokeInstruction("OP_INVOKE", chunk, offset);
        case OP_CLOSURE: {
            offset++;
            uint8_t constant = chunk->code[offset++];
            printf("%-16s %4d", "OP_CLOSURE", constant);
            printValue(chunk->constants.values[constant]);
            printf("\n");

            ObjFunction* function = AS_FUNCTION(
                chunk->constants.values[constant]
            );
            for(int j = 0; j < function->upvalueCount; j++) {
                int isLocal = chunk->code[offset++];
                int index = chunk->code[offset++];
                printf("%04d    |                     %s %d\n",
                    offset - 2, isLocal ? "local" : "upvalue", index);
            }
            return offset;
        }
        case OP_CLOSE_UPVALUE: 
            return simpleInstruction("OP_CLOSE_UPVALUE", offset);
        case OP_RETURN:
            return simpleInstruction("OP_RETURN", offset);
        case OP_CLASS:
            return constantInstruction("OP_CLASS", OP_CLASS, chunk, offset);
        case OP_INHERIT:
            return simpleInstruction("OP_INHERIT", offset);
        case OP_GET_SUPER:
            return constantInstruction("OP_GET_SUPER", OP_GET_SUPER, chunk, offset);
        case OP_INVOKE_SUPER:
            return invokeInstruction("OP_INVOKE_SUPER", chunk, offset);
        case OP_METHOD:
            return constantInstruction("OP_METHOD", OP_METHOD, chunk, offset);
        default:
            printf("unknown opcode %d\n", instruction);
            return offset + 1;
    }
}